Re: [AV Media Matters] Magnetic fields

[rohre@ARLUT.UTEXAS.EDU]

Added note to Charles Repka's excellent account of motor magnetic
fields of X Ray conveyors:

In another life, I worked on X-Ray equipment during school.  It can
get out of adjustment, and have unregulated high voltage, thus
increasing the X-Ray effects. X-Rays will eventually deteriorate
plastic base film of media, thus I encourage travelers to have ALL
media hand inspected, and not put it on the conveyor or thru the
X-Ray fields.

Until we learn the long term effects of newer non X-Ray scanning
equipment the FAA is implementing, I would also not subject anything
to checked luggage and to fields and scans. My operations have
archives far more valuable than the few moments to have a document
identifying the courier, and explaining why master media cannot be
scanned or X-Rayed.  In some cases, I have personally called for a
Supervisor, and that usually speeds up the inspection!  Like most
bureaucratic systems, they do not like to have to call in the
Chiefs.  But, if they do, they are more knowledgeable than the on
line inspectors. However, I am certain FAA has not completely
checked out the effects of various equipment upon archival media.
They fogged film before realizing that would be a big airport
problem for travelers.  The dose is lower now, but for film;
shielding packaging is still a good insurance or best of all, hand
inspection with you presenting the film and overseeing their
process.

Every instrument can get out of calibration and in the case of
scanners, can generate unwanted effects.  In developing the early
portal detectors, (Magnetic) (that you walk through at airports), we
had a lot of problems with the systems my then employer modified. As
most of you who travel have observed, there still is a wide
disparity in how those are set up.  Some are way too sensitive to
your ball point pen in a shirt pocket, small change, and other
normal traveler's property which a well balanced system is SUPPOSED
to ignore.  As the Earth's own fields shift, this can upset the
balance in a coil based magnetic system.  Most airports are so busy,
there is no apparent regular calibration for the scanners.
Unfortunately, most of this inspection process does not detect the
plastic weapons or explosives, and it remains to be seen how the FAA
will implement their newest systems that initially are set up to
scan checked luggage.  Eventually, they will need this more
comprehensive technology to scan persons, and the privacy issues are
already being debated with the advent of "Superman's vision"
systems.  And we will need to be alert for any stray effects fields
of newer technology as well.

Stuart Rohre
Applied Research Labs, U. Tx
Media Archives Lab